They are fully synthetic, so may not suit you, and the brand is fishing/outdoors oriented, but Southern Marsh makes very comfortable T shirts that feature 30 UPF in their “performance shirt” lines. Have seen no shrinkage and the arms are long.

As a pale guy whose wife likes the beach, they have been very helpful.

EDIT: I'm sure they are nowhere near the only brand to use that particular mix of fibers (mostly a variety of polyester/Spandex mixes depending on the shirt), just the one whose shirts I own. And the "fishing" bit is about the designs - very heavy on the fishing/hunting designs.